How to judge the bad board of an LCD TV?

The power light is on, but it doesn't start, and the motherboard burns! If the power light does not light up, it may be that the power strip is burned, not absolutely.

1. First of all, look at whether the red light of the machine is on, [the indicator light is on, it will not be turned on twice, or it will automatically return to the standby state after turning on] [no accompanying sound, or there is noise in the accompanying sound], etc., which are all problems with the motherboard circuit. So for this problem, you can first measure whether the power supply voltage of the motherboard circuit is normal. 2. If the above measurement of the power supply voltage of the motherboard circuit is normal, then the next measurement is to measure whether the voltage of all DC-DC voltage conversion circuit chips on the motherboard and the pins of each output terminal to the ground is normal, if it is normal, then the fault may be the main control chip on the motherboard is abnormal or damaged, etc.

1. Magnetization of the TV.

Causes of magnetization of the TV: The TV has been subjected to severe vibration, the degaussing resistance inside the TV is damaged, the magnetization is affected by the magnetic objects next to it, and the deflection coil or color pure magnetic ring in the TV is displaced.

Magnetization of the TV solution: After the TV is subjected to severe vibration, there will be more situations, and it is not certain whether it is the damage of the components or human factors. It is necessary to ask a professional maintenance personnel to repair it, if the screen can be displayed, except for the halo phenomenon of the screen.

If everything is normal, then a professional degausser. If it can't be solved, it is generally that the degaussing element inside is damaged, and the component should be replaced. Be careful not to place magnetic objects next to the TV, as this will have a big impact on the TV.

There is also a color system that has not been adjusted well, so you can adjust it yourself.

2. There is no electricity on the whole TV.

The reason for the lack of power of the whole machine: This is a very simple fault, which is mainly caused by the internal power supply and the external power supply of the TV. Generally, it is the failure rate of the external power supply.

It's going to be higher. What is more likely to be damaged are some small components in the machine, which are relatively small, such as: fuses, rectifier bridges.

power switches and much more. Another is the failure of the driver board, which causes the whole machine to have no power.

The whole machine has no power to solve: if it is the cause of the power part, it is relatively simple to overhaul, and the problem can be solved after replacing these parts. If it is a fault of the driver board, it is a little more complicated, to check whether the relevant voltage of the power supply is normal, the failure of the driver board will cause the two groups of power supplies to have no output voltage, as long as the voltage is problematic, the driver board must be a problem.

3. There is sound but no image.

Reasons for sound and no picture: The first suspicion is that there is a problem with the high-frequency head, which will directly lead to this situation. There is also the color system is not adjusted to the pair, and the brightness is not adjusted to come out, and the color system is checked by adjusting the remote control.

After the high-frequency head is damaged, there is no image input, so there is no image display on the TV screen, check whether the relevant parameters of the high-frequency head are normal, and then replace. Then there is the adjustment of the color system of the TV, which is also one of the reasons, but this is usually relatively rare.

When the TV is turned off, you can see the light of the TV at the moment of turning it off, and there is a little discharge sound, then it can be concluded that the picture tube of the TV is normal.

To be clear,If the TV motherboard is damaged,It's actually a TV motherboard,It's actually an integrated processing chip,As long as the motherboard is damaged,Basically, you can't do it lighter every day,It's that you can't enter the system and the like。

And your question is supplemented by the fact that there is a sound,It means that there is no problem with its volume control of these chips,And there is an image that shows that his graphics processing system and other ** systems are no problem,And there are only images around,There is no image in the middle,The only possibility is not that the motherboard is damaged,But the home screen of your TV is damaged。

And the main screen of the TV is basically 60 70% of the TV. And this kind of because it is an LCD screen,Now the mainstream is an LCD screen,This kind of screen damage is impossible to repair at all,It's all directly replaced,That is to say, you have to spend 60 to 70 of your TV** to replace this screen。

If the motherboard is damaged, basically there will be no screen that does not display an image in the middle, and the image is not displayed around the situation, which directly means that you can basically not do any operation, but you can see that in the charging state, the screen is emitted by a faint dark light, and the situation you said is that the screen is damaged, not the motherboard is damaged.

If this situation occurs,If it's a relatively old TV,There's no need to repair it at all,Replace it directly with a new TV,And then trade in the old one can also offset it。 If you do activities, depending on the price, from 200 500 yuan, and now the TV ** is really very cheap, buy a new one.

The TV has sound and image, and it is generally not that the motherboard is bad,The black screen in the middle may be the backlight is broken,Check the backlight power supply, if there is voltage, it should be the backlight strip is bad。

To determine the fault of the motherboard, you need to detect or replace the method, and the fault you describe is a backlight fault or a screen fault.

You shouldn't be this because the motherboard is broken, maybe the picture tube is broken, and the screen will be black, so you don't understand it yourself, you must find a professional home appliance maintenance master to check it for you to know.

Hello,1、If the logic board of the LCD TV fails,Usually the screen display will appear:black screen、White screen、Gray screen、Negative image、Noise point、Vertical band、The image is too bright or too dark, etc.,Different LCD screens generally need to choose different LVDS programs,When the program does not match, there will be more phenomena such as color inaccuracy or abnormal image,That is, the screen parameter is usually wrong。 2. If the screen of the LCD TV is faulty, there are usually the following phenomena:

1) Vertical lines are displayed on the screen: one or more vertical lines. (2) Horizontal lines are displayed on the screen:

One or more horizontal lines. (3) The screen is displayed with shadows: shadows on the corners of the screen, vertically distributed shadows on both sides of the screen, horizontally distributed shadows on the screen, etc.

4) Vertical ribbons are displayed on the screen: One or more vertical ribbons that continue from the top of the screen to the bottom edge. 3. Usually the logic board of the LCD TV can be repaired when it fails, but the display screen failure cannot be repaired, and the screen needs to be changed to restore normal; If the TV has the above two types of faults, it is recommended that the user contact the after-sales service of the TV in time to repair the TV.

How to tell if the LCD screen is broken LCD TV repair.

1. The characteristics of the damage to the LCD screen are: there are two main categories: one is physical damage, such as bad spots (bright spots or dark spots) on the screen, black belts or broken screens; The second is due to the failure of the row and column drive circuit or liquid crystal molecules, and the phenomenon of blurred screens and vertical bands appears.

Although the failure of the LCD screen after damage is similar to that of some faults after the motherboard or logic board is damaged, it is easy to see the subtleties of the LCD screen after careful observation. So the above fault just doesn't turn on, and it can't be judged that it's a problem with the screen. The above issues are dealt with as follows:

If the above machine is not turned on, first check whether the components in the power input circuit are normal, such as: power supply fuse, varistor, and anti-interference circuit components, etc. If the above checks are normal, then measure whether the voltages of each group at the output end of the main switching power supply circuit are normal.

If the above measurements are normal, but the power-on test machine failure is still there, in this case, measure whether the power supply voltage of the motherboard circuit is normal. After measuring the power supply voltage of the motherboard circuit is normal, then this problem is being measured, all DC-DC voltage conversion circuit chips on the motherboard, and the pins of each output terminal touch the ground to make the voltage normal.

1. Visually inspect the main chip, power supply, IC, filter capacitor and other wearing parts to see if there is obvious blackening or abnormal color;

2. Measure the resistance, check whether the power supply test points are short-circuited, whether the resistance becomes smaller, and whether the fuse is open-circuited;

3. Measure the voltage and check whether the power supply measurement point is normal (power supply VCC5V 12V, main chip 3 3V, 2 5V, 1 8V, 1 2V, etc., VAA14V, VGH20V, VGL 5 5V, VREF13V, VCOM 6V);

4. Measure whether the data exchange between the IC signal line to ground resistance LVDS DDR and the main chip slag is poor;

5. Check whether there is poor contact between the connecting cable and the logic board, and between the logic board and the screen.

In fact, the LCD TV logic board,In addition to the LCD LVDS program failure,Other faults are easy to repair。

In order to tell if the fault is caused by the logic board or the screen, you can follow the steps below:

Check if there isLine fault, whether there isDamaged or loosesituation.

Check that the TV backlight is on. If the TV's background light is on, then the logic board should be normal. If the background light of the key is not lit, then it may be a logic board orPower stripThere was a malfunction.

Check if there is an image on the TV screen. If there is no image on the screen, then it probably isScreen glitches。If there is an image on the screen, but the image quality is not good, then it may be a logic board failure.

Check if there are black stripes or smudges on the TV screen. If there are any of these phenomena, then it could beScreen glitches